Transthoracic needle biopsy with fluoroscopic or computed tomographic guidance is a well-established and safe method for diagnosing malignant and benign thoracic lesions. Nonetheless, ultrasound is as effective as computed tomography for the guidance of transthoracic biopsies of peripheral pulmonary lesions and mediastinal tumors, and it offers some advantages. In this case report, we exemplify the proper use of ultrasound for the percutaneous biopsy of a lung lesion, aiming to show that it can be a safe, inexpensive, rapid, and effective alternative to computed tomography in appropriate cases.